Understanding van der Waals Interaction John P. Perdew, Tulaner University, DMR 0854769

1. Understanding van der Waals InteractionJohn P. Perdew, Tulaner University, DMR 0854769 The van der Waals interaction between two atoms, molecules, or nanostructures is a weak long-range interaction arising from electron correlation. Only its short-range part is built into standard semilocal density functionals for electronic structure calculations in materials. We have found that standard ways to add in the long-range part (atom pairwise interactions or nonlocal approximations) fail for large fullerenes because of their near-metallicity and abnormal distribution of atoms. We have also found a way to sum up the infinite series of van der Waals terms for the binding energy curve, and how to remove an unphysical singularity (see figures for the interaction of two C_60 molecules). This should lead to better van der Waals corrections. Binding energy curves for the fullerene pair C60-C60. The curves show the leading contributions, and also a singular summation of the infinite van der Waals series.

2. Understanding van der Waals InteractionJohn P. Perdew, Tulaner University, DMR 0854769 An undergraduate physics major, Stephen Glindmeyer, joined our research group in January 2012, received summer research support from this grant, and contributed usefully to this work. Other group members include two research assistant professors, a postdoctoral fellow, and three graduate students. van der Waals Coefficients for Nanoclusters: Fullerenes Defy Conventional Wisdom, A. Ruzsinszky, J.P. Perdew, J. Tao, G.I. Csonka, and J.M. Pitarke. van der Waals Interaction as a Summable Asymptotic Series, J.P. Perdew, A. Ruzsinszky, J. Sun, S. Glindmeyer, and G.I. Csonka. Binding energy curves for C60-C60. The asymptotic van der Waals series has been summed to all orders in the inverse distance between the centers, with and without a singularity.